That link you gave me is fantastic, thanks! I contacted him to ask what he would charge to do a certain building, as my skills are not that good. Here's an example of the first few houses I made. Done in Lightwave. I have to take into account that the scene will have more than a hundred houses (see real model), along with bushes, trees, and whatnot, and I still have to render it really big. So I can't use really highpoly houses, unless at the foreground. It's quite a task I've set myself, and hope to get it done without too many sleepless nights.
I strive for the use of a few generic textures that I can call in Terragen, not use image maps for each building. So TG wouldn't have to load too many image maps. Then make them different from each other by using additional procedural colors. I don't know yet what my i7 16 gig can handle, but I don't want to overdo it.
I looked at google warehouse too, thanks.